Electric Motor System With Grounded Planetary Gear
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Solution Overview
Problem
Existing electric vehicle drive arrangements with a single motor or parallel motor configurations are susceptible to degradation due to adjustable output speed ratios and exhibit space inefficiencies, as seen in Bramson's system, which uses a planetary gear set where all gears function as either inputs or outputs, leading to increased complexity and potential for powertrain efficiency drops.
Innovation Solution
A motor system comprising two electric machines coupled via a planetary gear set with a ring gear, sun gear, and carrier, where one component is permanently grounded, allowing for synchronous operation at different speeds with a fixed gear ratio, enabling efficient combination of motors of varying sizes and reducing system complexity and susceptibility to degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electric motor is used to provide rotational energy, then the system structure is simple, but powertrain efficiency drops when operating outside the desired efficiency range
Solution Approach 1:
The single electric motor is segmented into two separate electric machines with different size and operating characteristics. Each machine operates within its optimal efficiency range, preventing the powertrain efficiency drop that occurs when a single motor operates outside its desired efficiency range.
Solution Approach 2:
The system dynamically selects which electric machine to operate based on operating conditions. The controller switches between the first and second electric machines to maintain optimal efficiency, allowing the system to adapt to varying load requirements while preserving energy.
2Loss of energy
If two motors are coupled in parallel to a gear set with adjustable output speed ratio, then system efficiency increases, but the system becomes more susceptible to degradation
Solution Approach 1:
The adjustable output speed ratio mechanism is extracted and replaced with a fixed ratio planetary gear set. This eliminates the complexity and degradation susceptibility associated with adjustable ratios while maintaining the efficiency benefits of having two electric machines operating in parallel.
Solution Approach 2:
Instead of using an adjustable gear ratio to optimize efficiency, the invention inverts the approach by using a fixed ratio gear set combined with selective motor operation. The controller manages which motor operates rather than adjusting the gear ratio, thereby improving reliability.
3Adaptability or versatility
If all gears in the planetary arrangement function as rotational input or output, then torque transfer is flexible, but space efficiency decreases
Solution Approach 1:
The planetary gear set is designed with one gear component serving dual functions: it acts as both a structural support element and a rotational input or output member. This multi-functionality reduces the number of separate components needed, improving space efficiency while maintaining torque transfer flexibility through the fixed ratio mechanism.
Data Source
AI summary
Methods and systems for an electric motor system are provided. In one example, a motor system is provided which comprises a first electric machine rotationally coupled to a second electric machine by a planetary gear set that has three components: a ring gear, a sun gear, and a carrier with a plurality of planet gears. In the system, the first electric machine varies in size from the second electric machine and one of the planetary assembly components is permanently grounded.